Twenty-six million people in America have chronic kidney disease (CKD). Diabetes is by far the leading cause of CKD (diabetic nephropathy), accounting for 44% of new cases of dialysis (in 2005). Current treatments including ACE inhibitors for CKD patients mainly focus on managing symptoms and disease complications. Despite the various treatments available, the five-year survival rate is ~33% and the mortality risk increases with kidney disease progression and secondary hyperparathyroidism. Vitamin D receptor modulators (VDRMs) have been shown to reduce proteinuria/albuminuria in diabetic nephropathy patients and also provide cardiovascular and survival benefits for CKD patients. Despite encouraging data on VDRM's potential renal, cardiovascular and survival benefits for the CKD patients, currently in the CKD field VDRM is only indicated for secondary hyperparathyroidism (with elevated PTH). Hypercalcemic toxicity that interferes with calcium homeostasis and detriments body functions is the limiting factor to expanded use of on-market VDRMs. A novel VDRM which retains the efficacy without the toxicity shared by current VDRMs would have significant clinical benefit. An ideal VDRM should be with no hypercalcemic toxicity in the efficacious dose range that could reduce PTH and provide cardiovascular benefits. Vidasym has taken a unique approach to discover novel VDRMs that are highly differentiated from existing VDRMs. In the clinically validated 5/6 nephrectomized uremic rat model Vidasym's VS-105 has no detectable hypercalcemic toxicity in the dose range that improves cardiovascular function and suppresses PTH to the normal level (vs. other VDRMs with overlapping dose ranges for efficacy and toxicity). Vidasym plans to develop VS-105 into a reimbursable prescription new drug to treat CKD patients. Initial focus for VS-105 in clinical studies is on diabetic nephropathy in CKD patients. Thus, a logical step is to determine the efficacy of VS-105 in diabetic nephropathy animal models. The specific aims of this Phase I study are: (1) To compare the therapeutic efficacy between VS-105 and paricalcitol (the VDRM that currently has the largest US market share) in blocking the progression of diabetic nephropathy in experimental models of type 1 and type 2 diabetes. (2) To elucidate the mechanism underlying the renoprotective effect of VS-105. Data from this phase I study will allow the advancement of VS-105 into Phase II IND-enabling studies including VS-105 synthesis scale-up, process development and pharmacokinetics, metabolism, safety and toxicology. The completion of Phase II studies will allow VS-105 to enter human clinical trials. Current VDRMs for secondary hyperparathyroidism alone achieve US$1+ billion in annual sales in 2010. Zemplar (paricalcitol) and Hectorol dominate the US dialysis market (>80%) due to their slightly less hypercalcemic toxic profile (~2 to 4 fold less toxic than generic Calcijex, the endogenous hormone calcitriol). A novel VDRM such as VS-105 for treating CKD could potentially achieve annual US sales at $1+ billion. PUBLIC HEALTH RELEVANCE: Vidasym's phase I STTR study will investigate the feasibility of using VS-105 to treat chronic kidney disease (CKD) related to diabetes (diabetic nephropathy). Diabetes is the leading causes of CKD. According to National Kidney Foundation, ~30% of patients with Type 1 (juvenile onset) diabetes and up to 40% of those with Type 2 (adult onset) diabetes eventually will suffer from kidney failure. In 2010 39.6% of people with diagnosed and 41.7% with undiagnosed diabetes had CKD. Globally > 350 million individuals have CKD and this number is projected to increase to >550 million by 2025 largely due to the growing epidemic of metabolic syndrome and diabetes. Although various modalities and substances are available for CKD, the number of diabetic CKD patients keeps increasing and the mortality rate for CKD patients remains high (~33%). There is an urgent medical need for the development of an effective and novel resuscitation approach for the treatment of diabetic nephropathy. Limitations of current therapy demonstrate that a new treatment approach such as VS-105 to reduce the need for dialysis and also reduce the mortality rate of CKD offers a significant opportunity for improved outcomes with substantial societal benefit.